Vacuum or modified atmosphere packaging methods and packaging machines are known.
Known packaging machines comprise first film feed means, a thermoforming station where containers are made in the first film inside which the product to be packaged will be introduced in a later step, second film feed means, and a sealing station that is supplied with both films and where the vacuum is formed or the gas is introduced in the container containing the product to be packaged. Subsequently in the sealing station, the second film is sealed to the first film such that the package is obtained. In a later step, cutting means comprised in the machine cuts the films longitudinally and transversely, separating the packages that have been formed.
Generally, as described in US2005/0173289A1, a packaging machine of this type comprises chains guiding the movement of the first film, said first film being fixed to said chains laterally, such that it remains taut.